Memory element and memory apparatus

ABSTRACT

A memory element includes a layered structure: a memory layer having a magnetization direction changed depending on information, the magnetization direction being changed by applying a current in a lamination direction of the layered structure to record the information in the memory layer, including a first ferromagnetic layer having a magnetization direction that is inclined from a direction perpendicular to a film face, a bonding layer laminated on the first ferromagnetic layer, and a second ferromagnetic layer laminated on the bonding layer and bonded to the first ferromagnetic layer via the bonding layer, having a magnetization direction that is inclined from the direction perpendicular to the film face, a magnetization-fixed layer having a fixed magnetization direction, an intermediate layer that is provided between the memory layer and the magnetization-fixed layer, and is contacted with the first ferromagnetic layer, and a cap layer that is contacted with the second ferromagnetic layer.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention is a Continuation of application Ser. No.14/330,748, filed Jul. 14, 2014, which is a Continuation of applicationSer. No. 13/675,789, filed Nov. 13, 2012, now U.S. Pat. No. 8,809,978,issued Aug. 19, 2014, and contains subject matter related to JapanesePatent Application JP 2011-261522 filed in the Japanese Patent Office onNov. 30, 2011, the entire contents of which being incorporated herein byreference.

BACKGROUND

The present technology relates to a memory element and a memoryapparatus.

In an information processing device, a high-speed and high-densityDynamic Random Access Memory (DRAM) is widely used as a random accessmemory.

However, the DRAM is a volatile memory that loses its information whenpower is removed. Accordingly, a non-volatile memory that does not loseits information is desirable.

A Magnetic Random Access Memory (MRAM) that records information bymagnetization of a magnetic material has been regarded as a possiblenon-volatile memory, and has been developed.

Recording is made in the MRAM by switching the magnetization using acurrent magnetic field, or directly injecting spin-polarized electronsinto a recording layer to induce magnetization switching (for example,see Japanese Unexamined Patent Application Publication No. 2004-193595).

Among them, spin injection magnetization switching that a recordingcurrent can be lowered as a size of an element is decreased is paidattention.

In order to further miniaturize the element, a method of using aperpendicular magnetization film where a magnetization direction of amagnetic material is directed perpendicularly (For example, see JapaneseUnexamined Patent Application Publication No. 2009-81215) has beenreviewed.

Japanese Unexamined Patent Application Publication No. 2004-193595discloses an equation of a switching time of a spin injectionmagnetization switching element using a perpendicular magnetizationfilm.

SUMMARY

However, according to the equation of the switching time shown inJapanese Unexamined Patent Application Publication No. 2004-193595, theswitching time of the magnetization of the spin injection magnetizationswitching element using the perpendicular magnetization film may belonger than that of the spin injection magnetization switching elementusing no perpendicular magnetization film.

It is desirable to provide a memory element and a memory apparatus thatcan be operated at high speed with less current.

According to an embodiment of the present technology, a memory apparatusis configured as described below.

In other words, the memory apparatus has a layered structure, including

a memory layer that a magnetization direction is changed correspondingto information,

a magnetization-fixed layer that the magnetization direction is fixed,

an intermediate layer that is formed of a non-magnetic material and isprovided between the memory layer and the magnetization-fixed layer and

a cap layer,

in which the information is recorded by applying a current in alamination direction of the layered structure to change themagnetization direction of the memory layer.

The memory layer includes a first ferromagnetic layer, a bonding layerand a second ferromagnetic layer laminated in the stated order, thefirst ferromagnetic layer is magnetically bonded to the secondferromagnetic layer via the bonding layer, the first ferromagnetic layeris contacted with the intermediate layer, the second ferromagnetic layeris contacted with the cap layer, one of the first ferromagnetic layerand the second ferromagnetic layer is an in-plane magnetization layerwhere in-plane magnetization occurs predominantly, the other is aperpendicular magnetization layer where perpendicular magnetizationoccurs predominantly, and the magnetization directions of the firstferromagnetic layer and the second ferromagnetic layer are inclined froma direction perpendicular to a film face.

A memory apparatus according to an embodiment of the present technologyincludes the memory element according to the embodiment of the presenttechnology, an interconnection that supplies a current flowing from thelamination direction to the memory element, and a current supplycontroller that controls the supply of current to the memory element viathe interconnection.

As the magnetization direction of the ferromagnetic layers of the memorylayer are inclined from the direction perpendicular to the film face, assoon as a current flows to the memory layer in the directionperpendicular to the film face (a lamination direction of each layer),an amplitude of a precession movement of the magnetization in eachferromagnetic layer is started to be increased. As compared with theconfiguration where the magnetization direction is not inclined, it ispossible to switch the magnetization direction in a shorter time.

Accordingly, when information is recorded by switching the magnetizationdirection in each ferromagnetic layer of the memory layer, it ispossible to shorten the switching time and decrease variability in theswitching time.

Thus, the amount of current for recording the information can bedecreased, and the information can be recorded in a short time.

Accordingly, the present technology can realize the memory element andthe memory apparatus that can operate at high speed with less current.

These and other objects, features and advantages of the presenttechnology will become more apparent in light of the following detaileddescription of best mode embodiments thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 a schematic perspective view of a memory apparatus according toan embodiment;

FIG. 2 is a cross-sectional view of a memory apparatus according to anembodiment;

FIG. 3 is a plan view of a memory apparatus according to an embodiment;

FIG. 4 is a cross-sectional view for illustrating a schematicconfiguration of an STT-MRAM memory element in the related art where amagnetization direction is perpendicular to a film face;

FIG. 5 is a schematic configuration cross-sectional view of a memoryelement according to a first embodiment;

FIG. 6 is a schematic configuration perspective view of a memory layeraccording to a first embodiment;

FIG. 7 is a schematic configuration cross-sectional view of a memoryelement according to a second embodiment;

FIGS. 8A and 8B are plots of a relationship between a time and aperpendicular component of the magnetization (Mi) of the memory layer ineach of the memory element in the past and the memory element accordingto an embodiment;

FIG. 9 is a plot showing a dependency of a writing error rate on acurrent supply time;

FIGS. 10A to 10E each show a Kerr measurement result of each sample inExperiment 1;

FIGS. 11A to 11D each show a Kerr measurement result of each sample inExperiment 1;

FIGS. 12A to 12E show a Kerr measurement result of each sample inExperiment 1;

FIGS. 13A and 13B each show an application of a memory element (amagnetoresistive effect element) according to an embodiment to acomposite magnetic head.

DETAILED DESCRIPTION OF EMBODIMENTS

The embodiments of the present technology will be described in thefollowing order.

<1. Schematic Configuration of Memory apparatus according to Embodiment>

<2. General Description of Memory Element according to Embodiment>

<3. First Embodiment>

<4. Second Embodiment>

<5. Simulation Results>

<6. Experiments>

<7. Alternative>

1. Schematic Configuration of Memory Apparatus According to Embodiment

Firstly, a schematic configuration of a memory apparatus will bedescribed.

FIGS. 1, 2 and 3 each show a schematic diagram of the memory apparatus.FIG. 1 is a perspective view, FIG. 2 is a cross-sectional view and FIG.3 is a plan view.

As shown in FIG. 1, in a memory apparatus according to an embodiment, amemory element 3 including a Spin Transfer Torque-Magnetic Random AccessMemory (STT-MRAM) that can hold information depending on a magnetizationstate is disposed in the vicinity of an intersection of two kinds ofaddress interconnections (for example, a word line and a bit line) thatare perpendicular with each other.

In other words, a drain region 8, a source region 7, and a gateelectrode 1 that make up a selection transistor for the selection ofeach memory element 3 are formed in a semiconductor substrate 10, suchas a silicon substrate, at portions isolated by an element isolationlayer 2. Among them, the gate electrode 1 functions also as an addressinterconnection (a word line) extending in the front-back direction inFIG. 1.

The drain region 8 is formed commonly with right and left selectiontransistors in FIG. 1, and an interconnection 9 is connected to thedrain region 8.

The memory element 3 having a memory layer that switches a magnetizationdirection by a spin torque magnetization switching is disposed betweenthe source region 7 and a bit line 6 that is disposed at an upper sideand extends in the right-left direction in FIG. 1. The memory element 3is configured with, for example, a magnetic tunnel junction element (MTJelement).

As shown in FIG. 2, the memory element 3 has two magnetic layers 12 and14. In the two magnetic layers 12 and 14, one magnetic layer is set as amagnetization-fixed layer 12 in which the direction of the magnetizationM12 is fixed, and the other side magnetic layer is set as amagnetization-free layer in which the direction of the magnetization M14varies, that is, a memory layer 14.

In addition, the memory element 3 is connected to each bit line 6 andthe source region 7 through upper and lower contact layers 4,respectively.

In this manner, when a current in the vertical direction (in alamination direction) is applied to the memory element 3, the directionof the magnetization M14 of the memory layer 14 can be switched by aspin torque magnetization switching.

As shown in FIG. 3, the memory apparatus is configured by disposing thememory elements 3 at intersections of a number of first interconnections(word lines) 1 and second interconnections (bit lines) 6 that aredisposed perpendicularly in matrices.

The memory element 3 has a planar circular shape and a cross-sectionshown in FIG. 2.

Also, the memory element 3 has the magnetization-fixed layer 12 and thememory layer 14.

The plurality of the memory elements 3 configures a memory cell of thememory apparatus.

In such a memory apparatus, it is necessary to perform writing with acurrent equal to or less than the saturation current of the selectiontransistor, and it is known that the saturation current of thetransistor decreases along with miniaturization. In order to miniaturizethe memory apparatus, it is desirable that spin transfer efficiency beimproved and the current flowing to the memory element 3 be decreased.

In addition, it is necessary to secure a high magnetoresistance changeratio to amplify a read-out signal. In order to realize this, it iseffective to adopt the above-described MTJ structure, that is, toconfigure the memory element 3 in such a manner that an intermediatelayer is disposed between the two magnetic layers 12 and 14 as a tunnelinsulating layer (tunnel barrier layer).

In the case where the tunnel insulating layer is used as theintermediate layer, the amount of the current flowing to the memoryelement 3 is restricted to prevent the insulation breakdown of thetunnel insulating layer from occurring. That is, it is desirable torestrict the current necessary for the spin torque magnetizationswitching from the viewpoint of securing reliability with respect to arepetitive writing of the memory element 3. The current necessary forthe spin torque magnetization switching is also called as switchingcurrent, memory current or the like.

Since the memory apparatus according to the embodiment is a non-volatilememory apparatus, it is necessary to stably store the informationwritten by a current. That is, it is necessary to secure stability(thermal stability) with respect to thermal fluctuations in themagnetization of the memory layer 14.

In the case where the thermal stability of the memory layer 14 is notsecured, a switched magnetization direction may be switched again due toheat (temperature in an operational environment), and result in aholding error.

The memory element 3 (STT-MRAM) in the memory apparatus is advantageousin scaling compared to the MRAM in the related art, that is,advantageous in that the volume can be small. However, as the volume issmall, the thermal stability may be deteriorated as long as othercharacteristics are the same.

As the capacity increase of the STT-MRAM proceeds, the volume of thememory element 3 becomes smaller, such that it is important to securethe thermal stability.

Therefore, in the memory element 3 of the STT-MRAM, the thermalstability is a significantly important characteristic, and it isnecessary to design the memory element in such a manner that the thermalstability thereof is secured even when the volume is decreased.

2. General Description about Memory Element According to Embodiment

Then, a general description about the memory element 3 according to theembodiment will be described.

Firstly, referring to the cross-sectional view of FIG. 4, a schematicconfiguration of a memory element 3′ in the STT-MRAM in the related artwill be described in which the magnetization direction of the memorylayer (the magnetization direction in an equilibrium state) isperpendicular to the film face.

As will become apparent from the following description, in the memoryelement 3 according to an embodiment of the present technology, thedirection of the magnetization M14 of the memory layer 14 (the directionof the magnetization M14 in an equilibrium state) will not beperpendicular to the film face. In the description referring to FIG. 4,the memory layer “14” of the memory element 3′ will be used as a matterof convenience.

As shown in FIG. 4, in the memory element 3′, a magnetization-fixedlayer (also referred to as a reference layer) 12 where a direction ofmagnetization M12 is fixed, an intermediate layer (non-magnetic layer:tunnel insulating layer) 13, a memory layer (free magnetization layer)14 where the direction of the magnetization M14 is variable and a caplayer 15 are laminated on an underlying layer 11 in the stated order.

Of these, in the magnetization-fixed layer 12, the direction of themagnetization M12 is fixed by high coercive force or the like. In thiscase, the magnetization direction of the magnetization-fixed layer 12 isfixed to in a direction perpendicular to the film face.

In the memory element 3′, information is stored by the direction of themagnetization M14 (magnetic moment) of the memory layer 14 havinguniaxial anisotropy.

Information is written into the memory element 3′ by applying a currentto in a direction perpendicular to the film face of each layer of thememory element 3′ (in other words, a lamination direction of each layer)to induce a spin torque magnetization switching in the memory layer 14.

Here, the spin torque magnetization switching will be briefly described.

For electrons there are two possible values for spin angular momentum.The states of the spin are defined temporarily as up and down.

The numbers of up spin and down spin electrons are the same in thenon-magnetic material. But the numbers of up spin and down spinelectrons differ in the ferromagnetic material.

Firstly, in the two ferromagnetic layers (the magnetization-fixed layer12 and the memory layer 14) laminated via the intermediate layer 13, thecase that the magnetization directions M12 and M14 are non-parallel andthe electrons are moved from the magnetization-fixed layer 12 to thememory layer 14 will be considered.

The electrons passed through the magnetization-fixed layer 12 are spinpolarized, that is, the numbers up spin and down spin electrons differs.

When the thickness of the intermediate layer 13 that is the tunnelbarrier layer is made to be sufficiently thin, the electrons reach theother magnetic material, that is, the memory layer (free magnetic layer)14 before the spin polarization is mitigated and the electrons become anon-polarized state in a common non-polarized material (the numbers upspin and down spin electrons are the same) in a non-polarized material.

A sign of the spin polarization in the two ferromagnetic layers (themagnetization-fixed layer 12 and the memory layer 14) is reversed sothat a part of the electrons is switched for lowering the system energy,that is, the direction of the spin angular momentum is changed. At thistime, the entire angular momentum of the system is necessary to beconserved so that a reaction equal to the total angular momentum changeby the electron, the direction of which is changed, is applied also tothe magnetic moment of the memory layer 14.

In the case where the current, that is, the number of electrons passedthrough per unit time is small, the total number of electrons, thedirections of which, are changed, becomes small so that the change inthe angular momentum occurring in the magnetization M14 of the memorylayer 14 becomes small, but when the current increases, it is possibleto apply large change in the angular momentum within a unit time.

The time change of the angular momentum with is a torque, and when thetorque exceeds a threshold value, the magnetization M14 of the memorylayer 14 starts a precession, and rotates 180 degrees due to uniaxialanisotropy of the memory layer 14 to be stable. That is, the switchingfrom non-parallel to parallel occurs.

On the other hand, when the directions of the magnetization M12 and M14of the two ferromagnetic layers are parallel and the electrons are madeto reversely flow from the memory layer 14 to the magnetization-fixedlayer 12, the electrons are then reflected at the magnetization-fixedlayer 12.

When the electrons that are reflected and spin-switched enter the memorylayer 14, a torque is applied and the direction of the magnetization M14of the memory layer 14 is switched so that it is possible to switch themagnetization M12 and M14 to non-parallel.

However, at this time, the amount of current necessary for causing theswitching is larger than that in the case of switching from non-parallelto parallel.

The switching from parallel to non-parallel is difficult to intuitivelyunderstand, but it may be considered that the magnetization M12 of themagnetization-fixed layer 12 is fixed such that the magnetic moment isnot switched, and the memory layer 14 is switched for conserving theangular momentum of the entire system.

As described above, the recording of 0/1 is performed by applying acurrent having a predetermined threshold value or more, whichcorresponds to each polarity, from the magnetization-fixed layer(reference layer) 12 to the memory layer 14 or in a reverse directionthereof.

Reading of information is performed by using a magnetoresistive effectsimilarly to the MRAM in the related art. That is, as is the case withthe above-described recording, a current is applied in a directionperpendicular to the film face (in the lamination direction of eachlayer). Then, a phenomenon in which an electrical resistance shown bythe memory element 3 varies depending on whether or not the direction ofthe magnetization M14 of the memory layer 14 is parallel or non-parallelto the direction of the magnetization M12 of the magnetization-fixedlayer (reference layer) 12 is used.

A material used for the intermediate layer 13 as the tunnel insulatinglayer may be a metallic material or an insulating material, but theinsulating material may be used for the intermediate layer 13 to obtaina relatively high read-out signal (resistance change ratio), and torealize the recording by a relatively low current. The element at thistime is called a ferromagnetic tunnel junction (Magnetic TunnelJunction: MTJ) element.

The above-described spin torque changes by an angle between thedirection of the magnetization M14 of the memory layer 14 and thedirection of the magnetization M12 of the magnetization-fixed layer(reference layer) 12.

When a unit vector representing the direction of the magnetization M14is specified as m1 and a unit vector representing the direction of themagnetization M12 is specified as m2, a magnitude of the spin torque isproportional to m1×(m1×m2). Herein, “x” means a cross product of thevectors.

In general, the magnetization M12 of the magnetization-fixed layer 12 isfixed to the easy axis of magnetization of the memory layer 14. Themagnetization M14 of the memory layer 14 has a tendency to direct theeasy axis of magnetization of the memory layer 14 itself. In this case,m1 and m2 are at 0 degree (parallel) or 180 degrees (non-parallel).

FIG. 4 illustrates the direction of the magnetization M14 and thedirection of the magnetization M12 when m1 and m2 are at 0 degree.

Thus, when m1 and m2 are at 0 degree or 180 degrees, the spin torquewill not work at all according to the above-described spin torqueequation.

However, in practice, as the magnetization M14 of the memory layer 14 israndomly distributed around the easy axis of magnetization of the memorylayer 14 due to thermal fluctuations, the spin torque works to inducethe magnetization switching, once the angle between the magnetizationM14 of the memory layer 14 and the magnetization M12 of the memory layer12 deviates from 0 degree or 180 degrees.

The time for inducing the magnetization switching (the switching time)depends on the distance from the magnetization M14 to the easy axis ofmagnetization. The longer the distance from the easy axis ofmagnetization is, the higher the speed of the magnetization switchingis.

As described above, the magnetization M14 of the memory layer 14 and theangle of the easy axis of magnetization are randomly distributed due tothermal fluctuations, resulting in variability of the switching time.

Even if the magnetization M14 is positioned close to (at a close angle)the easy axis of magnetization, in order to switch the magnetization athigh speed, it is necessary to flow a larger current.

The present inventors have diligently studied to operate the memoryelement at high speed with less current.

As a result, it has been found that the memory layer 14 has theconfiguration that the perpendicular magnetization layer whereperpendicular magnetization occurs predominantly is magnetically bondedto the in-plane magnetization layer where in-plane magnetization occurspredominantly via the bonding layer, whereby a magnetic interactionbetween the magnetization of the in-plane magnetization layer and themagnetization of the perpendicular magnetization layer causes eachmagnetization to be inclined from the direction perpendicular to thefilm face.

With such a configuration, it is possible to shorten the switching timeand decrease variability in the switching time.

According to the embodiment, in order to magnetically bond theperpendicular magnetization layer where perpendicular magnetizationoccurs predominantly and the in-plane magnetization layer where in-planemagnetization occurs predominantly via the bonding layer, Co—Fe—B havingperpendicular magnetic anisotropy is used.

In general, the ferromagnetic layer used for the memory layer or thelike has a significantly thin film thickness as compared with a filmsurface. In this case, once the magnetization of the ferromagnetic layerdirects to the perpendicular direction, a large diamagnetic field isprovided. By the interaction between the diamagnetic field and themagnetization, diamagnetic field energy (hereinafter referred to as Ed)increases. As a result, the magnetization cannot face stably to theperpendicular direction and will face to the in-plane direction in theequilibrium state.

However, the ferromagnetic layer may have perpendicular magneticanisotropy depending on the material and an interfacial state. In thiscase, perpendicular magnetic anisotropy energy (hereinafter referred toas Ea) induced by the perpendicular magnetic anisotropy acts on theferromagnetic layer. When the magnetization of the ferromagnetic layerfaces to the perpendicular direction of the film face, the netdiamagnetic field energy equals to Ed-Ea.

When the diamagnetic field energy is negative, i.e., Ed<Ea, themagnetization can face stably to the perpendicular direction. Such aferromagnetic layer is hereinafter referred to as “the perpendicularmagnetization layer where perpendicular magnetization occurspredominantly”.

Adversely, when the diamagnetic field energy is positive, i.e., Ed>Ea,the magnetization cannot face stably to the perpendicular direction.Such a ferromagnetic layer is hereinafter referred to as “the in-planemagnetization layer where in-plane magnetization occurs predominantly”.

In general, the Co—Fe—B ferromagnetic layer is the in-planemagnetization layer where in-plane magnetization occurs predominantly.

However, Co—Fe—B can be the perpendicular magnetization layer whereperpendicular magnetization occurs predominantly, so long as theconditions are satisfied.

Specifically, when the composition and the film thickness of the Co—Fe—Bfilm are within a certain range and the Co—Fe—B film is contacted withthe MgO film, it will be the perpendicular magnetization layer whereperpendicular magnetization occurs predominantly (for example, seeJapanese Patent Application No. 2010-200983).

The origin of the perpendicular magnetization anisotropy whereperpendicular magnetization occurs is said to be interfacial anisotropyat an interface between MgO and Co—Fe—B.

In addition, when both interfaces of the Co—Fe—B film are contacted withthe MgO film such as MgO/Co—Fe—B/MgO, the perpendicular magnetizationanisotropy will increase (for example, see Japanese Patent ApplicationNo. 2010-201526).

3. First Embodiment

The specific embodiments of the present technology will be describedbelow.

FIG. 5 shows a schematic configuration view (cross-sectional view) ofthe memory element 3 according to a first embodiment.

In the description below, a description is omitted as to the parts thatare the same as the parts already described by attaching the same signs.

As shown in FIG. 5, in the memory element 3 according to the embodiment,the magnetization-fixed layer (reference layer) 12 where the directionof magnetization M12 is fixed, the intermediate layer (non-magneticlayer: tunnel insulating layer) 13, the memory layer (free magnetizationlayer) 14 where the direction of the magnetization M14 is variable andthe cap layer 15 are laminated on the underlying layer 11 in the statedorder.

As described above, in the magnetization-fixed layer 12, the directionof the magnetization M12 is fixed in a direction perpendicular to thefilm face (upward in the Figure).

The memory element 3 according to the embodiment is different from theformer memory element 3′ in that the configuration of the memory layer14 is changed to have a multilayer configuration including theferromagnetic layers and the bonding layers.

Specifically, the memory layer 14 has a three-layered structureincluding a ferromagnetic layer 14 i, a bonding layer 14 c and aferromagnetic layer 14 p are laminated in the stated order.

The ferromagnetic layer 14 i is the in-plane magnetization layer wherein-plane magnetization occurs predominantly.

The ferromagnetic layer 14 p is the perpendicular magnetization layerwhere perpendicular magnetization occurs predominantly.

In the embodiment, the ferromagnetic layer 14 i is contacted with theintermediate layer 13, and the ferromagnetic layer 14 p is contactedwith the cap layer 15.

In the above-described configuration, the magnetization Mi of theferromagnetic layer 14 i and the magnetization Mp of the ferromagneticlayer 14 p are magnetically bonded via the bonding layer 14 c.

Here, in the bonding layer 14 c, non-magnetic metal such as Ta, Ru andthe like can be used.

An insulating material (a variety of oxides and the like) for formingthe tunnel insulating layer or non-magnetic metal that is used betweenthe magnetoresistive effect element and the magnetic layer can be usedfor the intermediate layer (non-magnetic layer) 13 between themagnetization-fixed layer 12 and the memory layer 14.

By using the insulating material as the material of the intermediatelayer 13, relatively high read-out signal (resistance change ratio) canbe provided, and it is possible to record at a relatively low current,as described above.

In the first embodiment, in order to provide the ferromagnetic layer 14p that is the perpendicular magnetization layer where perpendicularmagnetization occurs predominantly, an oxide such as MgO is used for thecap layer 15. Although not shown, the cap layer 15 is configured tolaminate non-magnetic metal such as Ta and Ru on the MgO layer, therebydesirably increasing the electrical conductivity.

A variety of magnetic materials used in the STT-MRAM in the related artcan be used for the magnetization-fixed layer 12.

For example, NiFe, TePt, CoPt, TbFeCo, GdFeCo, CoPd, MnBi, MnGa, PtMnSb,Co—Fe—B, Co—Cr based material and the like can be used. It is possibleto use magnetic materials other than these materials.

A read-out of information is performed by using a magnetoresistiveeffect similarly to the memory element 3′ in the related art. That is,as is the case with the above-described recording of information,current is applied to flow in a direction perpendicular to the film face(in the lamination direction of each layer). Then, a phenomenon is usedwhere an electrical resistance shown by the memory element 3 varies by arelative angle of the direction of the magnetization M12 of themagnetization-fixed layer 12 and the direction of the magnetization M14of the memory layer 14.

FIG. 6 shows the configuration of the memory layer 14 in further detail.

Here, the bonding layer 14 c is omitted for the sake of convenience.

In the memory element according to the embodiment, the memory layer 14has a cylindrical shape.

In order to describe the magnetization Mi and Mp directions, angles θ1and θ2 are defined as described layer.

Specifically, when an axis pieces through the memory layer 14 in aperpendicular direction is defined as a perpendicular axis aV, the angleθ1 is formed by the magnetization Mi and the perpendicular axis aV, theθ2 is formed by the magnetization Mp and the perpendicular axis aV.

As described above, in the magnetization Mi, the in-plane magnetizationoccurs predominantly, and in the magnetization Mp, the perpendicularmagnetization occurs predominantly.

Accordingly, when the magnetization direction is inclined from theperpendicular axis aV with the bond via the bonding layer 14 c, theangle θ1 will be greater than the angle θ2. In other words, themagnetization Mi is greatly inclined from the perpendicular axis aV.

The greater the relative angle of the magnetization M12 of the memorylayer 12 and the magnetization Mi is, the more the spin torqueincreases. The above-described configuration of the memory layer 14 canrealize the greater magnetization switching.

4. Second Embodiment

Next, FIG. 7 shows a schematic configuration view (cross-sectional view)of the memory element 20 according to a second embodiment.

In the memory element 20 according to the second embodiment, thelamination order of the memory layer 14 is different from the memoryelement 3 according to the first embodiment. Specifically, theferromagnetic layer 14 p, the bonding layer 14 c and the ferromagneticlayer 14 i are laminated in the stated order.

In this case, the ferromagnetic layer 14 p is contacted with theintermediate layer 13, and the ferromagnetic layer 14 i is contactedwith the cap layer 15.

In order to provide the ferromagnetic layer 14 p that is theperpendicular magnetization layer where perpendicular magnetizationoccurs predominantly, an oxide such as MgO is used for the intermediatelayer 13.

In the memory element 20 having the configuration as described above,the spin torque is determined by the relative angle of the magnetizationM12 of the memory layer 12 and the magnetization Mp.

In this case, since the angle θ2 is smaller than the angle θ1, the spintorque in the memory element 20 becomes smaller than that in the memoryelement 3 in the first embodiment. However, as compared with the memoryelement 3′ in the related art, the magnetization direction (themagnetization direction in an equilibrium state) of the memory layer 14is inclined. As a result, it is possible to switch the magnetization athigher speed.

As described for confirmation, in the memory apparatus according to thesecond embodiment, the memory element 20 is disposed instead of thememory element 3 in the memory apparatus having the configuration shownin FIGS. 1 to 3.

5. Simulation Results

In order to verify advantages of the memory elements (3, 20) inrespective embodiments as described above, macro spin modelmagnetization switching was simulated.

FIGS. 8A and 8B each shows a simulation result of a time change in aperpendicular component of the magnetization, when a current is applied.

FIG. 8A shows the simulation result of the memory element 3′ in therelated art, and FIG. 8B shows the simulation result of the memoryelement according to the embodiment. In FIG. 8B, as “the memory elementaccording to the embodiment”, the memory element 20 according to thesecond embodiment was used.

In FIGS. 8A and 8B, the abscissa axis represents the time elapsed afterthe current is applied, and the horizontal axis represents theperpendicular component of the magnetization. The upward directionapproaches to 1, and the downward direction approaches to −1. The timefor applying a current (also described as “a current supply time”) isset to 20 ns.

In the memory element 3′ in the related art, the magnetization M14 ofthe memory layer 14 is directed to the perpendicular direction in theequilibrium state. Since the spin torque does not work as it is, thecalculation is done by displacing 0.01 degrees from the perpendicularaxis aV.

In the calculation shown in FIG. 8B, the magnetization Mp of theferromagnetic layer 14 p is directed at angle of 29 degrees from theperpendicular direction in the equilibrium state, and the magnetizationMi of the ferromagnetic layer 14 i is directed at angle of 73 degreesfrom the perpendicular direction in the equilibrium state, respectively.

In the memory element 3′ in the related art, the direction of themagnetization M14 is adjacent to the direction perpendicular to the filmface, which may decrease the spin torque and the change in magnetizationmovement to the time change. Accordingly, in a time domain T1 in FIG.8A, there is almost no change in the magnetization direction, when thecurrent is started to be applied.

Here, the length of the domain T1 changes each time the recording ismade, depending on an initial angle of the magnetization. Therefore, thetime for inducing the magnetization switching is deviated, and asufficiently long recording time is necessary for switching themagnetization with certainty.

After the time domain T1, the direction of the magnetization M14 issteeply changed to induce the magnetic switching (a time domain T2).After a time domain T3 where the current is continued to be applied, thecurrent becomes zero in a time domain T4.

In contrast, in the memory element according to the embodiment, themagnetization Mp of the ferromagnetic layer 14 p is directed to thedirection inclined from the axis perpendicular to the film face.Accordingly, the magnetization Mp of the ferromagnetic layer 14 p towhich some spin torque is applied concurrently with the application ofthe recording current will start the switching movement promptly (a timedomain T5). At this moment, the magnetization Mi of the ferromagneticlayer 14 i will also start the switching movement together with themovement of the magnetization Mp, since the magnetization Mi of theferromagnetic layer 14 i is magnetically bonded to the magnetization Mp.

Thus, the memory element according to the embodiment realizes theswitching movement at high speed.

In addition, it can be confirmed that the memory element according tothe embodiment has no time domain where the change in the magnetizationmovement is small such as the time domain T1 shown in FIG. 8A. Thismeans that, by the memory element according to the embodiment, it ispossible to shorten the time for applying the recording current and alsodecrease variability in the switching time.

Here, during a time domain T6 where the current is continued to beapplied, the spin torque is applied to the magnetization Mp and themagnetization Mi to deviate them from the equilibrium state.

By the calculation from FIG. 8B, the angle of the magnetization Mp is156 degrees, and the angle of the magnetization Mi is 112 degrees.

When the current becomes zero in a time domain T7, it changes to theequilibrium state where the angle is inclined from the originalperpendicular axis aV. At this time, the angle of the magnetization Mpis 151 degree (180 degrees−29 degrees), and the angle of themagnetization Mi is 107 degrees (180 degrees−73 degrees).

Then, a relationship between a writing error rate and a current supplytime will be described.

FIG. 9 shows the relationship between a writing error rate (alogarithmic value) determined by the simulation and the current supplytime.

In FIG. 9, the curve C1 shows the result of the memory element 3′ in therelated art, and the curve C2 shows the result of the memory element (inthis case, the memory element 20) according to the embodiment,respectively.

As described above, in the memory element 3′ in the related art, theswitching time changes each time the recording is made, depending on aninitial angle of the magnetization. Therefore, even though the currentsupply time is the same, the magnetization switching may be induced ormay not be induced.

Here, the probability of not inducing the magnetization switching iscalled as a writing error rate.

As the current supply time is longer, the probability of inducing themagnetization switching also increases, resulting in a tendency todecrease the writing error rate. In other words, when the current supplytime is short, the probability of inducing the switching decreases, sothat the writing error rate tends to increase.

As apparent from FIG. 9, the curve C1 for the memory element 3′ in therelated art has a gentle slope that the writing error rate is decreasedslowly to the current supply time.

On the other hand, the curve C2 for the memory element according to theembodiment has a steep slope. In other words, the necessary currentsupply time of the memory element according to the embodiment is shorterthan that of the memory element in the related art when they arecompared at the same writing error rate.

This result also supports that the memory element according to theembodiment can write at high speed.

Although the simulation result of the memory element 20 according to theembodiment is shown in FIGS. 8 and 9, the memory element 3 in the firstembodiment can also provide an improved result as compared with thememory element 3′ in the related art.

6. Experiments

Here, in the configuration of the memory element according to theembodiment, by specifically selecting the film thickness of each layerconfiguring the memory layer 14, the experiments were performed forverifying the inclination of the magnetization direction from theperpendicular axis. The contents and the results are described in[Experiment 1], [Experiment 2] and [Experiment 3] below.

[Experiment 1]

On a silicon substrate having a thickness of 0.725 mm, a thermal oxidefilm having a thickness of 300 nm was formed, and then a Ta film (15nm), a Ru film (10 nm), a Pt film (1 nm), a Co film (1.2 nm), a Ru film(0.7 nm), a Co-64Fe-20B film (1.2 nm), a MgO film (0.8 nm), aCo-56Fe-30B film (x nm), a Ta film (0.35 nm), a Co-64Fe-20B film (0.8nm), a MgO film (0.85 nm), a Ru film (5 nm) and a Ta film (3 nm) wereformed in the stated order from the underlying film.

In this case, from the bottom, the Ta film and the Ru film correspond tothe underlying layer 11, the Pt film, the Co film, the Ru film and theCo-64Fe-20B film correspond to the magnetization-fixed layer 12 having asynthetic pin layer structure, the MgO film corresponds to theintermediate layer 13, the Co-56Fe-30B film corresponds to theferromagnetic layer 14 i, the Ta film corresponds to the bonding layer14 c, the Co-64Fe-20B corresponds to the ferromagnetic layer 14 p, theMgO film, the Ru film and the Ta film correspond to the cap layer 15. Inother words, it is the model of the memory element 3 according to thefirst embodiment.

The Co-56Fe-30B film which corresponded to the ferromagnetic layer 14 ihad a film thickness t of 1.5 nm, 1.6 nm, 1.65 nm, 1.7 nm or 1.8 nm ineach sample.

In the memory element of the STT-MRAM, the magnetization of one (themagnetization-fixed layer 12) of the two ferromagnetic layers that arecontacted with the non-magnetic layer (intermediate layer 13) isdesirably fixed.

As each sample in Experiment 1, a synthetic pin layer structure havingthe interlayer bonding was used for fixing the magnetization of thebottom Co-64Fe-20B film.

Using each sample as described above, Kerr was measured. FIGS. 10A to10E show the results.

In FIGS. 10A to 10E, the abscissa axis represents Kerr signal intensityin any unit that is proportional to the perpendicular component of themagnetization, and the horizontal axis represents the magnetic fieldapplied externally in the perpendicular direction.

FIGS. 10A, 10B, 10C, 10D and 10E show the results when the Co-56Fe-30Bfilm (the ferromagnetic layer 14 i) had the film thickness t of 1.5 nm,1.6 nm, 1.65 nm, 1.7 nm and 1.8 nm, respectively.

Firstly, the Co-56Fe-30B film having the film thickness of 1.5 nm wasconsidered.

As described above, the Co—Fe—B film that is contacted with the MgO filmmay be the perpendicular magnetization film depending on the interfacialanisotropy. The upper Co-64Fe-20B film corresponding to theferromagnetic layer 14 p induces the interfacial anisotropy at aninterface of the MgO film that is the cap layer 15, and becomes theperpendicular magnetization film.

At the same time, the Co-56Fe-30B film that is the ferromagnetic layer14 i induces the interfacial anisotropy at an interface of the MgO filmthat is the intermediate layer 13 becomes the perpendicularmagnetization film. This can be confirmed that the Kerr signal intensityproduced by applying external magnetic field of ±3 kOe to direct themagnetization direction entirely to the perpendicular direction, and theKerr signal intensity produced by applying external magnetic field of 0kOe to be the magnetization direction in the equilibrium state are aboutthe same. In other words, the magnetization coincides with theperpendicular axis aV in the equilibrium state, which does not form thememory element according to the embodiment of the present technology.

Next, the Co-56Fe-30B film having the film thickness of 1.6 nm or morewas considered.

When the film thickness is 1.65 nm or more, a dependency of the Kerrsignal intensity on the external magnetic field changes. In other words,the Kerr signal intensity produced by applying external magnetic fieldof ±3 kOe to direct the magnetization direction entirely to theperpendicular direction, and the Kerr signal intensity produced byapplying external magnetic field of 0 kOe to be the magnetizationdirection in the equilibrium state are different. This means that themagnetization is in the position inclined from the perpendicular axis aVin the equilibrium state, which forms the memory element 3 according tothe first embodiment of the present technology.

The dependency of the Co-56Fe-30B film (the ferromagnetic layer 14 i) inthe equilibrium state on the film thickness can be explained as follows:

The perpendicular magnetic anisotropy induced by the interfacialanisotropy tends to be decreased as the film thickness of theferromagnetic layer thickens. Therefore, as the film thickness thickens,the Co-56Fe-30 film is changed from the perpendicular magnetizationlayer where perpendicular magnetization occurs predominantly to thein-plane magnetization layer where in-plane magnetization occurspredominantly. In Experiment 1, it is considered that the boundaryexisted between 1.6 nm and 1.65 nm. The upper Co-64Fe-20B filmcorresponding to the ferromagnetic layer 14 p becomes the perpendicularmagnetization layer where perpendicular magnetization occurspredominantly, and the Co-56Fe-30B film corresponding to theferromagnetic layer 14 i becomes the in-plane magnetization layer wherein-plane magnetization occurs predominantly. By magnetic bonding via theTa film corresponding to the bonding layer 14 c, the magnetizationdirection is inclined from the perpendicular axis aV in the equilibriumstate.

[Experiment 2]

On a silicon substrate having a thickness of 0.725 mm, a thermal oxidefilm having a thickness of 300 nm was formed, and then a Ta film (15nm), a Ru film (10 nm), a Pt film (1 nm), a Co film (1.2 nm), a Ru film(0.7 nm), a Co-64Fe-20B film (1.2 nm), a MgO film (0.8 nm), aCo-56Fe-30B film (1.7 nm), a Ta film (x nm), a Co-64Fe-20B film (0.8nm), a MgO film (0.85 nm), a Ru film (5 nm) and a Ta film (3 nm) wereformed in the stated order from the underlying film.

In this case, from the bottom, the Ta film and the Ru film correspond tothe underlying layer 11, the Pt film, the Co film, the Ru film and theCo-64Fe-20B film correspond to the magnetization-fixed layer 12 having asynthetic pin layer structure, the MgO film corresponds to theintermediate layer 13, the Co-56Fe-30B film corresponds to theferromagnetic layer 14 i, the Ta film corresponds to the bonding layer14 c, the Co-64Fe-20B corresponds to the ferromagnetic layer 14 p, theMgO film, the Ru film and the Ta film correspond to the cap layer 15. Inother words, it is the model of the memory element 3 according to thefirst embodiment.

As the result of the former Experiment 1, the upper Co-64Fe-20B filmcorresponding to the ferromagnetic layer 14 p becomes the perpendicularmagnetization layer where perpendicular magnetization occurspredominantly, and the Co-56Fe-30B film corresponding to theferromagnetic layer 14 i becomes the in-plane magnetization layer wherein-plane magnetization occurs predominantly.

In Experiment 2, the Ta film corresponding to the bonding layer 14 c hadthe film thickness t of 0.35 nm, 0.4 nm, 0.45 nm, or 0.7 nm. The filmthicknesses of the Co-64Fe-20B film and the Co-56Fe-30B film were fixed.

FIGS. 11A to 11D show the results of the Kerr measurements using theabove-described respective samples.

FIGS. 11A, 11B, 11C and 11D show the results when the Ta film as thebonding layer 14 c had the film thickness t of 0.35 nm, 0.4 nm, 0.45 nmand 0.7 nm, respectively.

Firstly, the Ta film corresponding to the bonding layer 14 c having thefilm thickness of 0.35 nm or 0.4 nm was considered. As described inExperiment 1, the magnetization is inclined from the perpendicular axisaV in the equilibrium state within the range.

In contrast, when the Ta film corresponding to the bonding layer 14 chas the film thickness of 0.45 nm, there is a step in the course ofswitching. When the film thickness is 0.7 nm, the magnetizationswitching obviously occurs in two steps.

This is because the thicker the film thickness of the Ta filmcorresponding to the bonding layer 14 c is, the weaker the magneticbonding between the ferromagnetic layer 14 i and the ferromagnetic layer14 p, so that each magnetization moves independently. In Experiment 2,it is considered that the boundary in which two magnetizations moveintegrally existed between 0.4 nm and 0.45 nm.

It reveals that when the Ta film has the film thickness of 0.7 nm, twomagnetizations move independently, and become the perpendicularmagnetizations. When the film thickness of the Ta film is thin, theCo-56Fe-30B film corresponding to the ferromagnetic layer 14 i becomesthe in-plane magnetization layer where the in-plane magnetization occurspredominantly. Nevertheless, when the thickness of the Ta film thickens,the Co-56Fe-30B film corresponding to the ferromagnetic layer 14 ichanges to the perpendicular magnetization layer where perpendicularmagnetization occurs predominantly. This is because by thickening thefilm thickness of the Ta film, atom diffusion increases and theeffective film thickness of the Co-56Fe-30B film decreases.

As described above, according to Experiments 1 and 2, by selecting thethicknesses of the Co—Fe—B layer and the Ta layer appropriately, theCo-64Fe-20B film corresponding to the ferromagnetic layer 14 p becomesthe perpendicular magnetization layer where perpendicular magnetizationoccurs predominantly, and the Co-56Fe-30B film corresponding to theferromagnetic layer 14 i becomes the in-plane magnetization layer wherein-plane magnetization occurs predominantly. It is found that when themagnetic bonding via the Ta film corresponding to the bonding layer 14 chas an appropriate value, the magnetization direction in the equilibriumstate can be inclined from the perpendicular axis aV.

[Experiment 3]

On a silicon substrate having a thickness of 0.725 mm, a thermal oxidefilm having a thickness of 300 nm was formed, and then a Ta film (5 nm),a Ru film (5 nm), a Pt film (1 nm), a Co film (1.2 nm), a Ru film (0.7nm), a Co-64Fe-20B film (1.2 nm), a MgO film (0.8 nm), a Co-56Fe-30Bfilm (1.5 nm), a Ta film (0.45 nm), a Co-64Fe-30B film (x nm), a MgOfilm (0.8 nm), a Ru film (5 nm) and a Ta film (10 nm) were formed in thestated order from the underlying film.

In this case, from the bottom, the Ta film and the Ru film correspond tothe underlying layer 11, the Pt film, the Co film, the Ru film and theCo-64Fe-20B film correspond to the magnetization-fixed layer 12 having asynthetic pin layer structure, the MgO film corresponds to theintermediate layer 13, the Co-64Fe-20B film corresponds to theferromagnetic layer 14 p, the Ta film corresponds to the bonding layer14 c, the Co-56Fe-30B corresponds to the ferromagnetic layer 14 i, theMgO film, the Ru film and the Ta film correspond to the cap layer 15. Inother words, it is the model of the memory element 20 according to thefirst embodiment.

In Experiment 3, the Co-56Fe-30B film which corresponded to theferromagnetic layer 14 i had a film thickness t of 0.7 nm, 0.75 nm, 0.8nm, 0.85 nm or 0.9 nm in each sample.

In the memory element of the STT-MRAM, the magnetization of one (themagnetization-fixed layer 12) of the two ferromagnetic layers that arecontacted with the intermediate layer (the non-magnetic layer) isdesirably fixed. As each sample in Experiment 3, a synthetic pin layerstructure having the interlayer bonding was used for fixing themagnetization of the bottom Co-64Fe-20B film (the magnetization-fixedlayer 12).

Using each sample as described above, Kerr was measured. FIGS. 12A to12E show the results when the Co-64Fe-30B film corresponding to theferromagnetic layer 14 i had the film thickness t of 0.7 nm, 0.75 nm,0.8 nm, 0.85 nm and 0.9 nm, respectively.

In Experiment 3, when the Co-56Fe-30B film corresponding to theferromagnetic layer 14 i has the film thicknesses of 0.7 nm and 0.9 nm,the Kerr signal intensity produced by applying external magnetic fieldof ±3 kOe to direct the magnetization direction entirely to theperpendicular direction and the Kerr signal intensity produced byapplying external magnetic field of 0 kOe to be the magnetizationdirection in the equilibrium state are about the same. The magnetizationcoincides with the perpendicular axis aV in the equilibrium state, whichdoes not form the memory element according to the second embodiment.

On the other hand, when the Co-56Fe-30B film has the film thicknesses of0.75 mm, 0.8 nm and 0.85 nm, the Kerr signal intensity produced byapplying external magnetic field of ±3 kOe to direct the magnetizationdirection entirely to the perpendicular direction and the Kerr signalintensity produced by applying external magnetic field of 0 kOe to bethe magnetization direction in the equilibrium state are different. Thismeans that the magnetization is in the position inclined from theperpendicular axis aV in the equilibrium state, which forms the memoryelement 20 according to the second embodiment of the present technology.

The dependency of the Co-56Fe-30B film in the equilibrium state on thefilm thickness can be explained as follows:

The perpendicular magnetic anisotropy induced by the interfacialanisotropy tends to be increased as the film thickness of theferromagnetic layer thins, but tends to be decreased as the filmthickness of the ferromagnetic layer thickens. Therefore, theperpendicular magnetic anisotropy increases within a certain filmthickness range. The Co-56Fe-30B film corresponding to the ferromagneticlayer 14 i is the in-plane magnetization layer where in-planemagnetization occurs predominantly in the film thickness range in whichthe experiment is performed. It is considered that if there is someperpendicular magnetic anisotropy, the inclined magnetization by bondingwith the upper Co-64FE-20B film cannot be provided. In Experiment 3, itis considered that the film thickness range which provides the necessaryperpendicular magnetic anisotropy has the lower limit between 0.7 nm and0.75 nm, and the upper limit between 0.85 nm to 0.9 nm.

Within the film thickness range, the Co-64Fe-20B film corresponding tothe ferromagnetic layer 14 p becomes the perpendicular magnetizationlayer where perpendicular magnetization occurs predominantly, and theCo-56Fe-30B film corresponding to the ferromagnetic layer 14 i becomesthe in-plane magnetization layer where in-plane magnetization occurspredominantly. By magnetic bonding via the Ta film corresponding to thebonding layer 14 c, the magnetization direction is inclined from theperpendicular axis aV in the equilibrium state.

As described above, according to Experiment 3, by selecting thethicknesses of the Co—Fe—B layer, it is found that the memory elementaccording to the embodiment in which the magnetization direction in theequilibrium state is inclined from the perpendicular axis aV can beprovided.

7. Alternative

While the embodiments according to the present technology are described,it should be understood that the present technology is not limited tothe illustrative embodiments described above.

For example, the composition of the Co—Fe—B film should not be limitedto the illustrative compositions (Co:Fe:B=14:56:30 or Co:Fe:B=16:64:20).A variety of compositions can be employed without departing from thespirit and scope of the present technology.

In addition, the Co—Fe—B film may have a single composition or alaminated structure including a plurality of compositions. Furthermore,a non-magnetic element can be added.

Although an oxide such as MgO is cited as the material for inducing theperpendicular magnetic anisotropy to the Co—Fe—B film, it is not limitedto the oxide and a variety of materials can be used.

The material of the bonding layer 14 c is not limited to Ta, but may beany materials such as Zr, V, Cr, Zr, Mo, W, Ru and Mg that can inducethe magnetic bonding between the ferromagnetic layers.

The underlying layer 11 and the cap layer 15 may have a singlecomposition or a laminated structure including a plurality ofcompositions.

In addition, the magnetization-fixed layer 12 may be configured by asingle layer of a ferromagnetic layer, or may have a laminatedferri-pinned structure in which a plurality of ferromagnetic layers islaminated through a non-magnetic layer.

According to the present technology, the memory layer may have a filmstructure in which the memory layer is positioned at an upper or lowerside of the magnetization-fixed layer.

Furthermore, a so-called dual structure in which the magnetization-fixedlayers are provided at upper and lower sides of the memory layer can beemployed.

The memory elements 3, 20 according to the embodiment of the presenttechnology each have a configuration of the magnetoresistive effectelement such as a TMR element. The magnetoresistive effect element asthe TMR element can be applied to a variety of electronic apparatuses,electric appliances and the like including a magnetic head, a hard diskdrive equipped with the magnetic head, an integrated circuit chip, apersonal computer, a portable terminal, a mobile phone and a magneticsensor device as well as the above-described memory apparatus.

As an example, FIGS. 11A and 11B each show an application of amagnetoresistive effect element 101 having the configuration of thememory element 3 to a composite magnetic head 100. FIG. 11A is aperspective view shown by cutting some parts of the composite magnetichead 100 for discerning the internal configuration. FIG. 11B is across-sectional view of the composite magnetic head 100.

The composite magnetic head 100 is a magnetic head used for a hard diskapparatus or the like. On a substrate 122, the magnetoresistive effectmagnetic head according to the embodiment of the present disclosure isformed. On the magnetoresistive effect magnetic head, an inductivemagnetic head is laminated and thus the composite magnetic head 100 isformed. The magnetoresistive effect magnetic head functions as areproducing head, and the inductive magnetic head functions as arecording head. In other words, the composite magnetic head 100 isconfigured by combining the reproducing head and the recording head.

The magnetoresistive effect magnetic head mounted on the compositemagnetic head 100 is a so-called shielded MR head, and includes a firstmagnetic shield 125 formed on the substrate 122 via an insulating layer123, the magnetoresistive effect element 101 formed on the firstmagnetic shield 125 via the insulating layer 123, and a second magneticshield 127 formed on the magnetoresistive effect element 101 via theinsulating layer 123. The insulating layer 123 includes an insulationmaterial such as Al₂O₃ and SiO₂.

The first magnetic shield 125 is for magnetically shielding a lower sideof the magnetoresistive effect element 101, and includes a soft magneticmaterial such as Ni—Fe. On the first magnetic shield 125, themagnetoresistive effect element 101 is formed via the insulating layer123.

The magnetoresistive effect element 101 functions as a magnetosensitiveelement for detecting a magnetic signal from the magnetic recordingmedium in the magnetoresistive effect magnetic head. Themagnetoresistive effect element 101 may have the similar filmconfiguration (layer structure) to the above-described memory elements3, 20.

The magnetoresistive effect element 101 is formed in an almostrectangular shape, and has one side that is exposed to an oppositesurface of the magnetic recording medium. At both ends of themagnetoresistive effect element 101, bias layers 128 and 129 aredisposed. Also, connection terminals 130 and 131 that are connected tothe bias layers 128 and 129 are formed. A sense current is supplied tothe magnetoresistive effect element 101 through the connection terminals130 and 131.

Above the bias layers 128 and 129, the second magnetic shield 127 isdisposed via the insulating layer 123.

The inductive magnetic head laminated and formed on the above-describedmagnetoresistive effect magnetic head includes a magnetic core includingthe second magnetic shield 127 and an upper core 132, and a thin filmcoil 133 wound around the magnetic core.

The upper core 132 forms a closed magnetic path together with the secondmagnetic shield 127, is to be the magnetic core of the inductivemagnetic head, and includes a soft magnetic material such as Ni—Fe. Thesecond magnetic shield 127 and the upper core 132 are formed such thatfront end portions of the second magnetic shield 127 and the upper core132 are exposed to an opposite surface of the magnetic recording medium,and the second magnetic shield 127 and the upper core 132 come intocontact with each other at back end portions thereof. The front endportions of the second magnetic shield 127 and the upper core 132 areformed at the opposite surface of the magnetic recording medium suchthat the second magnetic shield 127 and the upper core 132 are spacedapart by a predetermined gap g.

In other words, in the composite magnetic head 100, the second magneticshield 127 not only magnetically shields the upper side of themagnetoresistive effect element 101, but functions as the magnetic coreof the inductive magnetic head. The second magnetic shield 127 and theupper core 132 configure the magnetic core of the inductive magnetichead. The gap g is to be a recording magnetic gap of the inductivemagnetic head.

In addition, above the second magnetic shield 127, thin film coils 133buried in the insulation layer 123 are formed. The thin film coils 133are formed to wind around the magnetic core including the secondmagnetic shield 127 and the upper core 132. Both ends (not shown) of thethin film coils 133 are exposed to the outside, and terminals formed onthe both ends of the thin film coil 133 are to be external connectionterminals of the inductive magnetic head. In other words, when amagnetic signal is recorded on the magnetic recording medium, arecording current will be supplied from the external connectionterminals to the thin film coil 133.

As described above, a lamination structure of the memory elementaccording to the embodiment of the present technology can be applied tothe reproducing head of the magnetic recording medium, i.e., themagnetoresistive effect element for detecting a magnetic signal from themagnetic recording medium.

The present disclosure may also have the following configurations.

(1) A memory element, including:

a layered structure including

-   -   a memory layer that has a magnetization direction changed        depending on information, the magnetization direction being        changed by applying a current in a lamination direction of the        layered structure to record the information in the memory layer,        including        -   a first ferromagnetic layer having a magnetization direction            that is inclined from a direction perpendicular to a film            face,        -   a bonding layer laminated on the first ferromagnetic layer,            and        -   a second ferromagnetic layer laminated on the bonding layer            and bonded to the first ferromagnetic layer via the bonding            layer, having a magnetization direction that is inclined            from the direction perpendicular to the film face,        -   one of the first ferromagnetic layer and the second            ferromagnetic layer being an in-plane magnetization layer            where in-plane magnetization occurs predominantly, the other            being a perpendicular magnetization layer where            perpendicular magnetization occurs predominantly,        -   a magnetization-fixed layer having a fixed magnetization            direction,        -   an intermediate layer that is provided between the memory            layer and the magnetization-fixed layer, and is contacted            with the first ferromagnetic layer, and        -   a cap layer that is contacted with the second ferromagnetic            layer.            (2) The memory element according to (1), in which the first            ferromagnetic layer is the in-plane magnetization layer, and            the second ferromagnetic layer is the perpendicular            magnetization layer.            (3) The memory element according to (2), in which

the angle formed by the magnetization of the first ferromagnetic layerand the direction perpendicular to the film face is greater than theangle formed by the magnetization of the second ferromagnetic layer andthe direction perpendicular to the film face.

(4) The memory element according to (1), in which

the first ferromagnetic layer is the perpendicular magnetization layer,and the second ferromagnetic layer is the in-plane magnetization layer.

(5) The memory element according to (4), in which

the angle formed by the magnetization of the first ferromagnetic layerand the direction perpendicular to the film face is smaller than theangle formed by the magnetization of the second ferromagnetic layer andthe direction perpendicular to the film face.

(6) The memory element according to (1) to (5), in which

the intermediate layer is a tunnel insulating layer.

(7) The memory element according to (1) to (6), in which the cap layerincludes an oxide layer.

(8) The memory element according to (1) to (7), in which

the first ferromagnetic layer and the second ferromagnetic layerincludes a Co—Fe—B layer.

(9) A memory apparatus, including:

a memory element having

-   -   a layered structure including        -   a memory layer that has a magnetization direction changed            depending on information, the magnetization direction being            changed by applying a current in a lamination direction of            the layered structure to record the information in the            memory layer, including            -   a first ferromagnetic layer having a magnetization                direction that is inclined from a direction                perpendicular to a film face,            -   a bonding layer laminated on the first ferromagnetic                layer, and            -   a second ferromagnetic layer laminated on the bonding                layer and bonded to the first ferromagnetic layer via                the bonding layer, having a magnetization direction that                is inclined from the direction perpendicular to the film                face,            -   one of the first ferromagnetic layer and the second                ferromagnetic layer being an in-plane magnetization                layer where in-plane magnetization occurs predominantly,                the other being a perpendicular magnetization layer                where perpendicular magnetization occurs predominantly,    -   a magnetization-fixed layer having a fixed magnetization        direction,    -   an intermediate layer that is provided between the memory layer        and the magnetization-fixed layer, and is contacted with the        first ferromagnetic layer, and    -   a cap layer that is contacted with the second ferromagnetic        layer;

an interconnection that supplies a current flowing from the laminationdirection to the memory apparatus; and

a current supply controller that controls the supply of current to thememory apparatus via the interconnection.

The present technology contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-261522 filed in theJapan Patent Office on Nov. 30, 2011, the entire content of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A memory element, comprising a layered structurecomprising: a memory layer including: a first ferromagnetic layer, abonding layer laminated on the first ferromagnetic layer, and a secondferromagnetic layer laminated on the bonding layer; afixed-magnetization layer having a fixed magnetization directionperpendicular to a film face of the fixed-magnetization layer; and anintermediate layer provided between the memory layer and thefixed-magnetization layer, wherein a magnetization direction in anequilibrium state of the first ferromagnetic layer and a magnetizationdirection in an equilibrium state of the second ferromagnetic layer arerespectively at a first and second predetermined angle relative to thefixed magnetization direction, wherein the first and secondpredetermined angles are not parallel or antiparallel to the fixedmagnetization direction and are not parallel to one another.
 2. Thememory element according to claim 1, wherein the first predeterminedangle is closer to a direction perpendicular to the film face than to adirection parallel to the film face, and the second predetermined angleis closer to the direction parallel to the film face than to thedirection perpendicular to the film face.
 3. The memory elementaccording to claim 2, wherein the first predetermined angle is greaterthan the second predetermined angle.
 4. The memory element according toclaim 1, wherein the first predetermined angle is closer to a directionparallel to the film face than to a direction perpendicular to the filmface, and the second predetermined angle is closer to the directionperpendicular to the film face than to the direction perpendicular tothe film face.
 5. The memory element according to claim 4, wherein thefirst predetermined angle is smaller than the second predeterminedangle.
 6. The memory element according to claim 1, wherein theintermediate layer is a tunnel insulating layer.
 7. The memory elementaccording to claim 1, further comprising a cap layer including an oxidelayer.
 8. The memory element according to claim 1, wherein the firstferromagnetic layer and the second ferromagnetic layer respectivelyinclude a Co—Fe—B layer.
 9. The memory element according to claim 1,wherein a magnetization of the memory layer is changeable by a currentapplied in the fixed magnetization direction.
 10. The memory elementaccording to claim 1, wherein the equilibrium state is a state where nocurrent is applied.
 11. A memory apparatus, comprising: a memory elementhaving a layered structure including: a memory layer including: a firstferromagnetic layer, a bonding layer laminated on the firstferromagnetic layer, and a second ferromagnetic layer laminated on thebonding layer; a fixed-magnetization layer having a fixed magnetizationdirection perpendicular to a film face of the fixed-magnetization layer;and an intermediate layer provided between the memory layer and thefixed-magnetization layer, wherein a magnetization direction in anequilibrium state of the first ferromagnetic layer and a magnetizationdirection in an equilibrium state of the second ferromagnetic layer arerespectively at a first and second predetermined angle relative to thefixed magnetization direction, wherein the first and secondpredetermined angles are not parallel or antiparallel to the fixedmagnetization direction and are not parallel to one another.
 12. Thememory apparatus according to claim 11, wherein the first predeterminedangle is closer to a direction perpendicular to the film face than to adirection parallel to the film face, and the second predetermined angleis closer to the direction parallel to the film face than to thedirection perpendicular to the film face.
 13. The memory apparatusaccording to claim 12, wherein the first predetermined angle is greaterthan the second predetermined angle.
 14. The memory apparatus accordingto claim 11, wherein the first predetermined angle is closer to adirection parallel to the film face than to a direction perpendicular tothe film face, and the second predetermined angle is closer to thedirection perpendicular to the film face than to the directionperpendicular to the film face.
 15. The memory apparatus according toclaim 14, wherein the first predetermined angle is smaller than thesecond predetermined angle.
 16. The memory apparatus according to claim11, wherein the intermediate layer is a tunnel insulating layer.
 17. Thememory apparatus according to claim 11, further comprising a cap layerincluding an oxide layer.
 18. The memory apparatus according to claim11, wherein the first ferromagnetic layer and the second ferromagneticlayer respectively include a Co—Fe—B layer.
 19. The memory apparatusaccording to claim 11, wherein a magnetization of the memory layer ischangeable by a current applied in the fixed magnetization direction.20. The memory apparatus according to claim 11, wherein the equilibriumstate is a state where no current is applied.